MARK COLVIN: Senior Coalition ministers are denying that the Nationals were tricked into supporting the indexation of petrol in last month's federal budget.

Yesterday the ABC reported senior Liberals boasting that before the budget the Government floated a change to the diesel fuel rebate as a way of getting the Nationals to agree to the petrol price change as the "lesser of two evils".

Labor is delighted at the suggestion of Coalition tension. It's used Question Time to goad the Nationals over the allegation that they were duped.

Political correspondent Louise Yaxley reports.

LOUISE YAXLEY: The most senior figures in the Government are denying that the Liberals tricked their junior Coalition partner by allowing people to think the diesel fuel rebate that is so important to miners, farmers and fishermen, might be cut back in the budget, and doing so as a way of winning agreement for reintroducing petrol tax indexation that John Howard froze more than a decade ago.

The Nationals Leader and Acting Prime Minister, Warren Truss, says it is just not true.

WARREN TRUSS: The assertions made by the Leader of the Opposition and the report on the ABC are simply wrong, are simply wrong.

ANDREW BROAD: Skulduggery in politics? What are we - is that a news story? Really?

LOUISE YAXLEY: And Darren Chester:

DARREN CHESTER: Oh, it's really a question of who do you believe in these type of he said, she said situations? You've got senior Cabinet ministers prepared to stand in front of these cameras and answer questions and a so-called Liberal source sneaking around the back blocks of the press gallery making statements which haven't been substantiated.

So, I've got no doubt that a Liberal source may have provided information to a journalist, but the essence of the story on whether those events transpired the way described in the article, I think, are a complete furphy.

LOUISE YAXLEY: This morning the suggestion that the Government was never serious about any change to the diesel fuel rebate gained a little extra weight when Treasury officials told Labor's Penny Wong the department had not provided advice about it.

PENNY WONG: Ah, well, no, I just want to clarify what the answer Mr Heferen just gave was. I think the answer was essentially Treasury hasn't provided that advice to this or previous governments. Is that correct?

ROB HEFEREN: That's correct.

PENNY WONG: Thank you. So, it was never actually considered?

LOUISE YAXLEY: So Labor kept trying to exert pressure on the Coalition in Question Time, beginning with the Opposition Leader Bill Shorten.

BILL SHORTEN: I refer to reports of Liberals boasting about playing the Nationals like a banjo, over their broken promise to increase fuel tax.

LOUISE YAXLEY: But the Government was hardly surprised by the questions and Agriculture Minister Barnaby Joyce was ready. He said it was the first question he'd received from the Labor Party since becoming a minister so he certainly didn't hold back on the enthusiasm.

BARNABY JOYCE: We've got a question about a rumour. A rumour! A rumour. So I've heard another rumour. Here's a rumour: I've heard that the Member for Sydney wants the Leader of the Opposition's job.

(Chamber erupts)

Here's another rumour: I've heard that someone from the New South Wales right got convicted by the ICAC for corruption. Oh hang on! That's not a rumour; that's a truth - Eddie Obeid.

LOUISE YAXLEY: The Greens are long-time campaigners against the diesel fuel rebate, especially for the mining sector and the Greens Deputy Leader Adam Bandt seized on the reports of a trick to try a different tactic.

ADAM BANDT: Thank you Madame Speaker. I seek leave to move the following motion: that in light of reports that Government Members of Parliament have been tricked into supporting the petrol tax increase, this House urges the Government to reconsider its unfair budget, including the proposal to raise $10 billion in revenue by removing the fuel tax credit for miners, but keeping it for farmers.

LOUISE YAXLEY: Mr Bandt's motion was seconded by the independent member for Indi, Cathy McGowan, but the Government used its numbers to stop both Mr Bandt and Ms McGowan from speaking.

She says her constituents had contacted her today asking what had happened.

CATHY MCGOWAN: I think there was two things about it that I thought was really interesting: there's the actual substance of the issue about the budget and the budget decisions, but also, there's the sense that people have that Government, the deal-making that goes on in the background and then who benefits.

And in this particular case, there was a lot of discussion about who are the beneficiaries of this particular deal if it did take place. So there was two things that I actually wanted to have the discussion on in Parliament today was 1) the substance of the argument, but probably more importantly for me is how decisions are made and how we, as politicians, represent our communities.